FOCUSED INJECTION OF VACUUM-ARC PLASMAS INTO CURVED MAGNETIC FILTERS

Thin films of high quality can be deposited using vacuum arc plasmas when the macroparticles which are produced along with the plasma in the cathode spots are removed by curved magnetic filters (''ducts''). In order to improve the deposition efficiency of a vacuum arc plasma source coupled to a magnetic filter, the effect of a magnetically focused plasma injection into such a filter has been investigated. Maximum plasma output was found at an optimum focusing field strength of 20-40 mT with an optimum duct bias of +20 V with respect to the anode potential (ground potential). The maximum output is by a factor of 20-30 greater than without focusing field and the duct at ground potential. This significant effect at relatively low injection field strength indicates that not only the magnetic field distribution but also the plasma current distribution is essential for an efficient plasma transport.